Meta Data Within a Data Warehouse
Metadata (meta data, or sometimes metainformation) is "data about other data", of any sort in any media. An item of metadata may describe an individual datum, or content item, or a collection of data including multiple content items and hierarchical levels, for example a database schema. In data processing, metadata is definitional data that provides information about or documentation of other data managed within an application or environment.
A D V E R T I S E M E N T
Metadata would document data about data elements or attributes, (name, size, data type, etc) and data about records or data structures (length, fields, columns, etc) and data about data (where it is located, how it is associated, ownership, etc.). Metadata may include descriptive information about the context, quality and condition, or characteristics of the data. It may be recorded with high or low granularity.
Data warehouse metadata systems are sometimes separated into two sections:
- back room metadata that are used for Extract, transform, load functions to get OLTP data into a data warehouse
- front room metadata that are used to label screens and create reports
Meta-data Management involves storing information about other information. With different types of media being used references to the location of the data can allow management of diverse repositories. URLs, images, video etc. may be referenced from a triples table of object, attribute and value.
With different knowledge domains the boundaries of the meta data for each must be managed since any general ontology is not of use to experts in one field whose language is knowledge domain specific.
Following are the types of metadata in a data warehouse:
- Source System Metadata
- Data Staging Metadata
- DBMS metadata